454 Starts..Hops on plane, backfires and stalls. Restarted

[BajabossJD]

Hi Guys,

Odd issue the last two times I took the boat out:

3 times ago it ran great. Started great and had nice power. Went about 14 miles and on the last mile, it backfired a little. I was low on gas so I backed it down and made it back to dock.

Last time I took it out (before today) It was harder to start...Didnt have much power to plane but once I plane..It cruised at 3k RPMs for about 10 miles and then backfired and stalled. It was extremly hard to start that day. I had to have it towed as it would start and then die after 30 seconds while cruising.

Today (after I replaced the coil, checked loose connection on red/white ignition wire and installed a new fuel filter) it started great. I figured the loose red/white wire was causing that issue and since I cleaned it up..I figured that made it start easier.

I hopped on plane around 3k and it went about a mile before major backfire and stalling. It restarted right away. I was trying to troubleshoot this and it never seemed to choke and stall on take off, but more so after 40-60 seconds of running a rpm higher than 1700rpm It idles great and doesnt stall.


Starting became harder throughout the day and I was able to idle it home. I took a video.

When I got back to dock I saw that the red/white wire had a loose connection (again). Would that wire cause these issues? Also, when I was checking the cap while engine was running, one of the wires gave me a nice shock!


New fuel filter, new carb, new coil, 1 year old distributor, I opened gas cap to ensure it was a vent issue.

Thoughts?

Thanks,
Joe

 

[BajabossJD]

It coughs at the 2:00 minute mark.

 

[wrench 3]

Did you check the contents of the fuel water separator?

 

[alldodge]

Hi Guys,

Odd issue the last two times I took the boat out:

3 times ago it ran great. Started great and had nice power. Went about 14 miles and on the last mile, it backfired a little. I was low on gas so I backed it down and made it back to dock.

Last time I took it out (before today) It was harder to start...Didnt have much power to plane but once I plane..It cruised at 3k RPMs for about 10 miles and then backfired and stalled. It was extremly hard to start that day. I had to have it towed as it would start and then die after 30 seconds while cruising.

Today (after I replaced the coil, checked loose connection on red/white ignition wire and installed a new fuel filter) it started great. I figured the loose red/white wire was causing that issue and since I cleaned it up..I figured that made it start easier.

I hopped on plane around 3k and it went about a mile before major backfire and stalling. It restarted right away. I was trying to troubleshoot this and it never seemed to choke and stall on take off, but more so after 40-60 seconds of running a rpm higher than 1700rpm It idles great and doesnt stall.


Starting became harder throughout the day and I was able to idle it home. I took a video.

When I got back to dock I saw that the red/white wire had a loose connection (again). Would that wire cause these issues? Also, when I was checking the cap while engine was running, one of the wires gave me a nice shock!


New fuel filter, new carb, new coil, 1 year old distributor, I opened gas cap to ensure it was a vent issue.

Thoughts?

Thanks,
Joe

I 'm thinking this is a carb engine and not EFI. Sure helps to know what were working with, engine serial number or year?

TB-4 or 5?

Is the red/wht wire actually a wht/red (white wire with red tracer)?

Have you checked fuel pump pressure?

 

[BajabossJD]

Its a 95 454, Carb with Thunderbolt 4.

I had a similar issue once when the belt was loose that drives the water / mechanical fuel pump..but it would only happen to slip at higher rpm..I would back off it and it would grip again and keep going. I tightened it and it was fine ever since.

It's just really odd that its gotten progressivly worse in the 3 trips out. If anything, the gas was much fresher the last 2 days. I have it rack stored at a really nice place on the water, with top quality dock fuel. Whats the easiet way to check the fuel pressure? Do I install the gauge on a T?

Thanks,
Joe

 

[alldodge]

Its a 95 454, Carb with Thunderbolt 4.

I had a similar issue once when the belt was loose that drives the water / mechanical fuel pump..but it would only happen to slip at higher rpm..I would back off it and it would grip again and keep going. I tightened it and it was fine ever since.

It's just really odd that its gotten progressivly worse in the 3 trips out. If anything, the gas was much fresher the last 2 days. I have it rack stored at a really nice place on the water, with top quality dock fuel. Whats the easiet way to check the fuel pressure? Do I install the gauge on a T?

Thanks,
Joe

Sure sounding like a fuel issue and your carb is running out of fuel. Could be a restriction or pump problem.

Yes. disconnect the fuel line between the filter and carb and install a Tee. Use one of the vacuum fuel pump tester. Fuel pressure should be between 4 to 7 psi. If the reading is good at idle try it out while running and see if it changes

http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=0X2DT4PP5H4RYE6646P6

 

[BajabossJD]

Great. I will swing by the store and get it out on the water and check it out. I'll report back!

Thanks again,
Joe

 

[BajabossJD]

AllDodge: With the fuel line being a hard line from the filter to the carb, does this gauge install at the carb inlet, or down by the outlet of the filter? If it was rubber hose, I would think it would be easy. With this being steel tubing, I am not sure how to install this plastic T?

Thanks,
Joe

 

[alldodge]

AllDodge: With the fuel line being a hard line from the filter to the carb, does this gauge install at the carb inlet, or down by the outlet of the filter? If it was rubber hose, I would think it would be easy. With this being steel tubing, I am not sure how to install this plastic T?

Thanks,
Joe

The Tee can be installed at either end, pressure will be the same. Some have used some rubber fuel line and attached to the steel line with hose clamp, then use a hose barbed fitting an attached it to the carb or filter end. Others have removed the steel line and used barbed hose fittings at both ends to make it easier. My suggestion would be replace the hole line with rubber temporally. Take the steel line to an auto parts store and they should be able to find some fittings.

 

[alldodge]

Another idea would be to remove plug from the other output (arrow going out) and install a fitting there to attach the gauge.

 

[Bondo]

Ayuh,.... The fuel filter should be on the vacuum(tank) side of the fuel pump,....

Not 'tween the fuel pump, 'n carb,....

 

[alldodge]

Your right, it sounded way to easy a way to do it. The filter protects the pump, I knew that, one of my duh moments :facepalm:

 

[Tail_Gunner]

I dont beleive a carb has enough fuel in the bowl to run a 454 that long at 2000 plus rpm for 2 minute's id be willing to bet your fuel pump diaphragm is leaking aka shot.....Now that if if it has a old mechanical pump on it.

 

[BajabossJD]

UPDATE:

I worked on the boat most of the day today. Since the fuel pump was new and has less than 15 hours on it..I started to look at the belt driving the pump. I did see small rubber shavings on the back of my bench seat...which made me think I was having possible slippage.

I purchased a new belt, installed it (so fun without taking off the top water pump pulley..miserable). I then replaced the old spark plug wires as they looked rough.

When changing the wires out, I notice a black burnt tear in of the boots on cylinder 5. I then noticed the plug was loose.

I put the new wires on and tightened the #5 plug and it ran awful. Wouldn?t stay running..it was a miss for sure.

I pulled #5 plug and the electrode was burnt off! Not sure if the fuel starvation did that..or a possible arcing wiring. I have attached a pic.

I put a new plug in it and took it for a ride.. It shot up on plane..secondary?s kicked in and I was running 4200rpm (which is about what the engine did before the rebuild). 15 hours on the rebuild...

My fear is that the electrode is tearing up my cylinder, although it ran good and no odd noises were apparent.

Thanks for your input everyone...Still wondering what the heck happened.

Joe

 

[BajabossJD]

No Title

 

[Bondo]

Ayuh,.... Looks like Detonation from a lean condition,....

The remnants of that plug are long gone out the exhaust pipe,...

I'd pull, inspect, 'n probably change the other 7 plugs,....

 

[alldodge]

Check your timing, you may have some parts of your engine going out the exhaust

 

[wrench 3]

The loose spark plug can't dissipate its heat to the cylinder head and can cause its own detonation. It could have damage the piston but it's unlikely. That's more of a two stroke problem. Also the loose pieces should have been small enough to spit out of the exhaust without causing any problems.

 

[callen369]

I had a plug looking similar.....ended up with a bent valve. Better compression test that cylinder and see what you have. If it's good, then most likely those pieces are gone and probably didn't hurt anything.